Optical data communication systems have become the preferred medium for the transmission of information in the form of high speed data. In typical optical transmission systems, electrical signals representing binary data are converted into optical signals. The optical signals are transmitted via optical transmission links to an optical receiver and converted back to electrical signals. An optical transmitter typically includes a light source such as a light emitting diode or a laser and generates a modulated optical output signal varying between high and low light output, representing the logical 1's and 0's of a digital data stream. An optical receiver, commonly referred to as a detector, typically includes a light sensitive device which generates electrical-output signals in response to optical input signals.
The primary advantage of optical transmission is the high data rates, e.g. in the giga bit (billion bits) per second range, which can be achieved in optical transmission medium, such as fiber optic systems. Significant improvements have been made in recent years in high speed optical data transmitting devices in order to take advantage of the capability of the optical transmission medium. One such high speed data transmission transmitting device is described in U.S. Pat. No. 5,210,637, issued May 11, 1993. This device uses a layer of superconductive material to modulate the light output of a standard light source such as a light emitting diode or a laser. It is a property of the superconductive material layer that it reflects light rays when it's in the superconducting state and that it is transparent to light rays in a non-superconducting state. The superconductive layer is switched between the superconducting and non-superconducting states by a modulation circuit operating at a high frequency. The superconductive material can be switched between the "on" and "off" states much faster than the conventional light source. Thus, higher data rates are achieved.
There seems to be an ever growing need in communications systems for higher information transfer rates. Currently, the information transfer rates are limited not by the transmission medium or the transmitters but by the receivers, which are not capable of operating at the same rate as the optical transmitters and optical transmission medium. Typically, in optical transmission systems, an additional system is added to handle the necessary traffic when the optical receiver of the existing system has reached its capacity. For example, in a system having a transmitter and a transmission medium capable of transmitting at the rate of 2 gigabits per second and a detector capable of receiving it at the rate of 1 gigabit per second, the capacity of the transmission system is limited to the capability of the detector. Thus, if a customer's needs require a transmission rate greater than 1 gigabits per second, a second transmission system, including a transmitter, a transmission medium and a detector will have to be supplied at substantial extra cost.